1. Field of the Invention
The present invention relates generally to solid nutrient media (SNM). More particularly, the present invention relates to an apparatus comprised of devices for making and plating a solid nutrient medium and methods thereof.
2. Background Information
Solid nutrient media (SNM) have various uses in microbiology, health care, the food industry, biotechnology, ecology and research. Microorganisms can proliferate on the surface of media (“direct method”) or inside media (“pour method”). The majority of microorganisms, such as bacteria, actinomycetes, fungi, and yeasts, i.e., hundreds of thousands of different species, are able to grow on nutrient agars. Nutrient agars are vital to the operation of microbiological laboratories. These laboratories rely on SNM for the growth of microorganisms which can exist in an investigated sample, for maintenance of microorganism collections for research purposes or quality control, for environmental control of indoor and outdoor air and for wash-outs from surfaces such as instruments, equipment, work surfaces and walls.
Samples containing microorganisms can be deposited on SNM by direct transfer of a liquid or solid sample on the surface of the SNM, by transfer filter with cells after filtration, or by impression of SNM onto an investigated surface.
Billions of growth plates (“Petri plates”) are used world-wide for different microbiological purposes, and well over 80-90% of currently used methods are based on preliminary growth of microorganisms, typically on solid media. For example, in 1999, the United States food industry conducted 144 million quality control tests, in which over 100 million of these tests required the use of nutrient agars (T. R. Weschler, American Clinical Laboratory, April 2001). This number does not include the millions of growth plates used in medical, veterinarian, biochemical, pharmaceutical, environmental, agricultural, research and educational microbiological laboratories. Thus, the total amount of growth plates used annually in the United States alone is in the hundreds of millions.
Petri/growth plates, therefore, are a vital part of microbiological analytical procedures, but they also are a substantial portion of a laboratory's expenses.
Since its introduction in 1877, growth plates, also referred to as Petri plates or Petri dishes, have remained largely unchanged. The typical Petri plate is a shallow cylindrical plate with a lid, in which air is allowed to enter the plate for aeration by passing through a slot between the lid and the plate. Much effort by microbiologists in the last century has been focused on the improvement of existing nutrient media and creating different nutrient media for the growth of different kinds of microorganisms. Numerous varieties of media have been created, the majority of which are in a solid phase with an agar base. Petri plates, however, have undergone far less changes over the years. For example, glass Petri plates have been replaced with plastic (i.e., polystyrene, polycarbonate) disposable plates, which have eliminated the costly and time-consuming process of cleaning and autoclaving. Several different shapes of Petri dishes (such as rectangular) and sizes have appeared on the market. Some plates currently are being manufactured with multiple inner compartments, which allows for the use of different media or additives in the same plate. For example, Nunclon® multidishes (Nunc, Inc.) are manufactured with 4 to 48 wells (cylindrical and rectangular) under one lid. These plates have found use in various fields, such as cytology and virology.
There exists a need, therefore, to provide a simpler, more efficient, cost-effective apparatus for manufacturing and plating of solid nutrient medium.